Vortex tube having at least two generators

ABSTRACT

A vortex tube according to an embodiment of the present disclosure includes a cold and heat separation chamber; a cold air outlet provided at an end of the cold and heat separation chamber, a generator provided between the cold air outlet and the cold and heat separation chamber, a hot air outlet provided at another end of the cold and heat separation chamber and including a hot air adjusting valve, and an outer tube cover having a compressed air inlet and surrounding the cold and heat separation chamber at a predetermined gap while blocking the cold and heat separation chamber at an outside thereof, so that introduced compressed air can be supplied into the generator, wherein the compressed air flowing through the compressed air inlet generates rapid rotating wind by passing through the generator to be moved into the cold and heat separation chamber to separate cold and heat from each other.

CROSS REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

This application claims benefit under 35 U.S.C. 119(e), 120, 121, or365(c), and is a National Stage entry from International Application No.PCT/KR2020/014715, filed Oct. 27, 2020, which claims priority to thebenefit of Korean Patent Application No. 10-2020-0106553 filed in theKorean Intellectual Property Office on Aug. 24, 2020, the entirecontents of which are incorporated herein by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a vortex tube and, more particularly,to a vortex tube having at least two generators to have improvedperformance when compared to a conventional vortex tube.

2. Background Art

The vortex tube (which is also called Ranque-Hilsch vortex tube)separates compressed air into a hot flow and a cold flow. When thecompressed air is injected toward a swirl chamber, the air isaccelerated and rotated at a high velocity. Only air rotated outside thetube is discharged from the tube due to a conical nozzle at the tube.The rest of the compressed air not discharged from the tube receives aforce returning the air in the opposite direction and is returned togenerate a vortex inside an outer vortex.

In other words, the vortex tube is a revolutionary cooling device thatseparates the supplied general compressed air (3-10 kg/cm²) into the hotand cold flows without electricity or any chemicals. When the compressedair is supplied into the vortex tube through a pipe, the compressed airis primarily supplied into the swirl chamber and is rotated at a highvelocity of about 1,000,000 RPM. When the rotated air (first vortex) ismoved toward a hot air outlet, a portion of the air is dischargedthrough the hot air outlet (30° C.˜90° C.) by an adjusting valve and therest of the air is returned from the adjusting valve to generate asecond vortex and then is discharged through a cold air outlet. A flowof the second vortex loses heat as the second vortex passes through alower pressure area inside the flow of the first vortex and is movedtoward the cold air outlet.

The cold air discharged through the cold air outlet of the vortex tubeis used in various industries. For example, the cold air is applied invarious field, such as machine operation cooling, CNC milling cuttingcooling, grinding, cutting, drill cooling, welding operation cooling ina dockyard, electronic product assembly cooling, and local cooling in asemiconductor factory.

The vortex tube has various advantages in addition to not requiring arefrigerant. For example, the vortex tube has advantages, such asimprovement of work efficiency, being maintenance-free, clean cooling,tool life extension, easy maintenance, instantaneous cooling, etc.

Recently, a rapid cooling function is increasingly used in combinationwith a precision machine or an electronic device by using cold of thevortex tube. In this case, the temperature of the discharged coldbecomes an important factor influencing performance.

However, although the vortex tube has been developed for over 150 yearsand has various uses, there have not been many attempts to improve theperformance of the product by changing the structure thereof. The aboveproblem is caused from reasons such that the vortex tube is not composedof many elements and the principle thereof is still not clearly known.

SUMMARY

Accordingly, the present disclosure has been made keeping in mind theabove problems occurring in the related art, and an objective of thepresent disclosure is to provide a vortex tube configured to lower thetemperature of discharged cold air, so that the efficiency of rapidcooling required for precision machinery or electronic devices amongfunctions of the vortex tube is improved and precision operation withoutcausing environmental pollution is possible.

Another objective of the present disclosure is to propose a vortex tubehaving at least two generators generating rapid rotating wind, thegenerators being partitioned by a sleeve, to lower the temperature ofdischarged cold air and thus to significantly improve the efficiency ofrapid cooling.

A further objective of the present disclosure is to provide a vortextube having an outer tube cover with a compressed air inlet surroundinga cold and heat separation chamber to facilitate storage and usage andto pre-cooling the cold and heat separation chamber with introducedcompressed air.

A further objective of the present disclosure is to provide a vortextube having a counterflow prevention cap inserted in a temperatureadjusting valve in preparation for difficulty of discharging hot air tothe outside of the vortex tube when the vortex tube is in an area whereoutside pressure is high.

An objective of the present disclosure is not limited to theabove-mentioned objectives, and other objectives not mentioned will beclearly understood by one of ordinary skill in the art to which thepresent disclosure belongs (hereinbelow, ‘those skilled in the art’) inthe following description.

In order to accomplish the above objective and to perform characteristicfeatures of the present disclosure, the present disclosure provides avortex tube configured as follows.

The vortex tube includes: a cold and heat separation chamber; a cold airoutlet provided at an end of the cold and heat separation chamber; agenerator provided between the cold air outlet and the cold and heatseparation chamber; a hot air outlet provided at another end of the coldand heat separation chamber and including a hot air adjusting valve; andan outer tube cover having a compressed air inlet and surrounding thecold and heat separation chamber at a predetermined gap while blockingthe cold and heat separation chamber at an outside thereof, so thatintroduced compressed air may be supplied into the generator, whereinthe compressed air flowing through the compressed air inlet generatesrapid rotating wind by passing through the generator to be moved intothe cold and heat separation chamber to separate cold and heat from eachother.

According to the above embodiment of the present disclosure, acounterflow prevention cap may be inserted in the hot air outletincluding the hot air adjusting valve.

According to another embodiment of the present disclosure, a vortex tubemay include: a cold and heat separation chamber; a cold air outletprovided at an end of the cold and heat separation chamber; a firstgenerator, a sleeve, and a second generator provided between the coldair outlet and the cold and heat separation chamber; a compressed airinlet provided at a portion close to the first generator and the secondgenerator and configured to supply compressed air into the firstgenerator and the second generator; and a hot air outlet provided atanother end of the cold and heat separation chamber and including a hotair adjusting valve, wherein an outlet of the sleeve may have a diameterlarger than a diameter of an entrance of the cold air outlet and smallerthan an inner diameter of each of the generators.

In addition, the vortex tube may include a third generator in additionto the second generator.

According to the present disclosure, the vortex tube is configured tolower the temperature of discharged cold air so that the efficiency ofrapid cooling required for precision machinery or electronic devicesamong functions of the vortex tube is improved and precision operationwithout causing environmental pollution can be realized. Accordingly,since the vortex tube of the present disclosure includes at least twogenerators generating rapid rotating wind, which are partitioned by thesleeve, to lower the temperature of discharged cold, the efficiency ofthe rapid cooling can be significantly improved.

The vortex tube of the present disclosure includes the outer tube coverwith the compressed air inlet surrounding the cold and heat separationchamber. Accordingly, storage and usage of the vortex tube can be easierand the cold and heat separation chamber can be pre-cooled with theintroduced compressed air.

The vortex tube of the present disclosure includes the counterflowprevention cap inserted in the temperature adjusting valve. Accordingly,difficulty for hot air to be discharged from the outside of the vortextube occurring when the vortex tube is in the area with high outsidepressure can be prevented.

Effects of the present disclosure are not limited to the above-mentionedeffects, and other effects not mentioned are clearly recognized by thoseskilled in the art in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a conventional vortex tube in contrast to thepresent disclosure.

FIG. 2 is a view showing a vortex tube having two generators accordingto a first embodiment of the present disclosure.

FIG. 3 is a view showing a vortex tube having two generators accordingto a second embodiment of the present disclosure.

FIG. 4 is a view showing a vortex tube having two generators accordingto a third embodiment of the present disclosure.

FIG. 5 is an exploded-perspective view showing the vortex tube of thethird embodiment shown in FIG. 4.

FIG. 6 is a view showing a vortex tube having three generators accordingto a fourth embodiment of the present disclosure.

FIG. 7 is a view showing a hot air adjusting part of the aboveembodiments, the hot air adjusting part having a counterflow preventioncap inserted therein to efficiently discharge hot air.

DETAILED DESCRIPTION

In the following description, “cold ratio” is the ratio of the amount ofair exiting a cold side to the amount of supplied compressed air. Whenthe cold ratio is 40%, the ratio of the amount of the compressed airconsumption to the amount of cold side discharged air is 100:40.

“Rapid rotating wind” means rotating air generated such that compressedair is supplied into a vortex tube through a pipe and is primarilysupplied into a vortex (swirl) chamber to be rotated at an ultra-highvelocity of about 1,000,000 RPM. The rapid rotating wind is referred toas “vortex” or “cyclone”. These terms have the same meaning.

In the following description, the structural or functional descriptionspecified to exemplary embodiments according to the concept of thepresent disclosure is intended to describe the exemplary embodiments, soit should be understood that the present disclosure may be variouslyembodied.

It should be understood that the exemplary embodiments according to theconcept of the present disclosure are not limited to the embodimentswhich will be described hereinbelow with reference to the accompanyingdrawings, but various modifications, equivalents, additions andsubstitutions are possible, without departing from the scope and spiritof the invention.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement, from another element. For instance, a first element discussedbelow could be termed a second element without departing from theteachings of the present disclosure. Similarly, the second element couldalso be termed the first element.

It will be understood that when an element is referred to as being“coupled” or “connected” to another element, it can be directly coupledor connected to the other element or intervening elements may be presenttherebetween.

In contrast, it should be understood that when an element is referred toas being “directly coupled” or “directly connected” to another element,there are no intervening elements present.

The terms used herein to describe a relationship between elements, forexample, “between”, “directly between”, “adjacent”, or “directlyadjacent” should be interpreted in the same manner as those describedabove.

In the following description, the same reference numerals will be usedto refer to the same or like elements. Meanwhile, the terms used hereinto describe a relationship between elements, for example, “between”,“directly between”, “adjacent”, or “directly adjacent” should beinterpreted in the same manner as those described above.

An element expressed in a singular form in this specification may beplural elements unless it is necessarily singular in the context. Theterms “comprise” and/or “comprising” means inclusion of a shape, number,process, operations, member, element, and/or a group of those, but donot mean exclusion of or denial of addition of another shape, number,process, operation, element, and/or a group of those.

Hereinbelow, embodiments of the present disclosure will be described indetail with reference to accompanying drawings.

FIG. 1 is a view showing a conventional vortex tube in contrast to thepresent disclosure. Furthermore, FIG. 1 is a comparative example incontrast to the embodiments shown in FIGS. 2, 3, and 4 disclosed in thepresent disclosure.

Figures shown in the drawings represent an actual device produced andtested by the applicant in the drawings, and there is one generator3000, and six generator wings 3010 are provided for a purpose of thegenerator. Each of six air intake grooves 3020 has a size of height of0.3 and width of 0.5 mm. An entrance 305 of the cold air outlet has adiameter of 2.2 mm.

FIGS. 2 and 3 have a difference of having two generators (300 and 400)and a sleeve (500, 510) located between the two generators in comparisonwith FIG. 1. In case of the generator wings 301, 401 provided for thegenerator to be serve as the generator, the first generator 300 hasthree generator wings 301 and the second generator 400 has threegenerator wings 401.

In case of air intake grooves 302, 402 formed between the generatorwings 301, 401, the first generator 300, 310 has three air intakegrooves 302, and the second generators 400 has three air intake grooves402. Each of the air intake grooves 302, 402 has the same size of heightof 0.3 and width of 0.5 mm as the air intake grooves provided in thevortex tube shown in FIG. 1.

The reason for limiting the numerical value of the vortex tube asdescribed above is to accurately compare an effect by testing the vortextube of the present disclosure in the same state as the related artshown in FIG. 1. However, in actual industrial application, thoseskilled in the art may change the number, size, etc. as much as neededon the basis of the operating principle of the vortex tube.

The reason, the number of the air intake grooves in FIG. 1 is six; FIGS.2 and 3 respectively have the total six air intake grooves; and all theair intake grooves have the same size, is to control the volume ofcompressed air, so that the same volume of the compressed air suppliedto operate and measure the vortex tube in the same condition. In thisway, the effect of the invention shown in FIGS. 2 and 3 may beobjectively measured. In FIGS. 1 to 3, the entrance of the cold airoutlet has a diameter of 2.2 m.

A thickness of the sleeve 510 in FIG. 2 is not a sensitive problem.However, a diameter of a sleeve entrance 505 and a diameter of a sleeveoutlet 507 are the same. Therefore, it is preferable that a rapidrotating wind diameter 307 of the first generator 300 has the samediameter as the diameter of the sleeve entrance 505. In FIG. 2, thediameter of the sleeve entrance 505 is 4.5 mm.

In FIG. 3, a thickness of the sleeve 500 affects the inclination of aninclined portion of the sleeve so as to affect the effectiveness of thevortex tube. Therefore, those skilled in the art may change the number,size, etc. as needed on the basis of the operating principle of thevortex tube. In the embodiment shown in FIG. 3, the sleeve with athickness of 2 mm is used.

A point in the above configuration is the relationship between adiameter of an entrance 305 of a cold air outlet, an inner diameter of acold and heat separation chamber 210, diameters of the sleeve entrance505 and the sleeve outlet 507. It is preferable that the rapid rotatingwind diameter 307 of the first generator 300 may be slightly differentfrom the diameter of the sleeve entrance 505, but be equal to thediameter of the sleeve entrance 505.

The diameter of the sleeve entrance 505 may be changed as needed, butthe diameter thereof is fundamentally formed equal to or larger than thediameter of the sleeve outlet 507. In addition, the diameter of thesleeve outlet 507 is fundamentally formed larger than the diameter thanthe diameter of the entrance 305 of the cold air outlet and smaller thanthe inner diameter of the cold and heat separation chamber 210.

The diameter of the sleeve outlet 507 may be changed as needed on thepremise that the first generator 300, 320 and the second generator 400generate rapid rotating wind on the basis of a value obtained by addingthe diameter of the entrance 305 of the cold air outlet and the innerdiameter of the cold and heat separation chamber 210 and dividing thesum by 2 to allow the flow in a direction of the cold and heatseparation chamber 210 to be efficiently performed.

Whether or not the first generator 300, 320 and the second generator 400generate the rapid rotating wind to efficiently perform the flow in thedirection of the cold and heat separation chamber is significantlyaffected by the air intake grooves 302, 402 and a value of obtained bysubtracting the diameter of the entrance 305 of the cold air outlet fromthe inner diameter of the cold and heat separation chamber 210.

The size of the air intake grooves 302, 402 is small and the valueobtained by subtracting the diameter of the entrance 305 of the cold airoutlet from the inner diameter of the cold and heat separation chamber210 is large. Therefore, the diameter of the sleeve outlet 507 mayfurther deviate from the value optioned by adding the diameter of theentrance 305 of the cold air outlet to the inner diameter of the coldand heat separation chamber 210 and dividing the sum by 2.

Those skilled in the art can determine an appropriate value of thediameter of the sleeve outlet 507 through repeatedly experiments byrecognizing the principle of operation of the present disclosure.

Generally, it is preferable that the diameter of the sleeve outlet 507satisfies [the diameter of the entrance of the cold air outlet+{(theinner diameter of the cold and heat separation chamber−the diameter ofthe entrance of the cold air outlet)/2±(the inner diameter of the coldand heat separation chamber−the diameter of the entrance of the cold airoutlet)/4}].

FIG. 4 is a view showing the vortex tube shown in FIG. 3, wherein anouter tube cover 700 surrounding the cold and heat separation chamber210 causes an effect that the compressed air flowing into the vortextube through a compressed air inlet 110 cools the cold and heatseparation chamber 210 with high temperature. Furthermore, a hot airadjusting valve 230 with a different shape is shown in the drawing.

Hereinbelow, the derivation of a comparative example and embodimentswill be described.

The vortex tubes shown in FIGS. 1 to 3 are tested and compared to eachother under the same conditions. The specifications of the manufacturedvortex tubes are as shown in FIGS. 1 to 3, and metal used in the vortextubes is SUS 316L.

The thickness of the sleeve is 2 mm and diameters of the sleeve entrance505 and the sleeve outlet 507 in FIG. 2 are 4.5 mm. The diameter of thesleeve entrance 505 in FIG. 3 is 7 mm and the diameter of the sleeveoutlet 507 is 4.5 mm. The compressed air supplied into the vortex tubesis controlled to remain at 7 bar continuously.

Experiments were conducted 5 times each by dividing the cold ratio intofive stages of 30%, 32%, 34%, 36%, 38%, and 40%. Between theexperiments, the temperature of the vortex tube was lowered to 15° C. byforcibly cooling so that following experiments were started in a stablestate.

As a result of the experiment, discharge temperature at a cold side ismeasured, and the measurement time was determined in consideration thatthe temperature reaches a steady state in 1 minute, and cold dischargetemperatures, which appear in exactly 3 minutes and 4 minutes after thecompressed air supply time, was measured and averaged. In theexperiment, the compressed air supplied in the vortex tube is controlledto generate the rapid rotating wind (cyclone) of 1,200,000 RPM.

As a result of the measurement, it was found that the vortex tube withthe two generators as shown in FIGS. 2 and 3 is more efficient than theconventional vortex tube in FIG. 1. The reason of the above result isestimated as follows. For example, when 100% of compressed air generatesthe rapid rotating wind from one generator, a large volume of thecompressed air is naturally moved forward along an outside an outerportion of an inside surface of the cold and heat separation chamber210.

However, a large volume of the compressed air may be absorbed into acold vortex flowing through a center portion of the cold and heatseparation chamber 210 to the entrance of the cold air outlet.

Accordingly, when the vortex tube includes the two generators, a volumeof the compressed air supplied into the first generator 300, 310 is ahalf of the total volume of the compressed air. A volume of a portion ofthe rapid rotating wind generated by the first generator 300, 310, theportion being absorbed in the cold vortex returned to the entrance 305of the cold air outlet (volume that is population parameter, actually,is a value of multiplying population parameter by absorption rate) maybe theoretically reduced to 50% of the total volume.

When the sleeve is inclined, the rapid rotating wind generated from thefirst generator 300, 310 is discharged through the sleeve without lossand is moved to the cold and heat separation chamber 210.

Under the above condition, 50% of the compressed air supplied throughthe compressed air inlet generates the rapid rotating wind through thesecond generator 400. The rapid rotating wind is generated by the firstgenerator 300, 310 and is located at an outer portion of the rapidrotating wind that has a slightly reduced diameter while passing throughthe inclined sleeve. Accordingly, 100% of the rapid rotating wind may bemoved toward the cold and heat separation chamber without contact withthe cold vortex.

Therefore, the vortex tube with the two generators of the presentdisclosure may be considered to generate cold air colder than the vortextube with the single generator. Of course, the diameter of the sleeveoutlet 507 is larger than the diameter of the entrance 305 of the coldair outlet. Conventionally, it is preferable that the diameter of thesleeve outlet 507 is a value equal to ½ of the sum of the inner diameterof the cold and heat separation chamber 210 and the diameter of theentrance 305 of the cold air outlet.

According to the present disclosure, the inner diameter of the cold andheat separation chamber 210 is 7 mm and the diameter of the entrance 305of the cold air outlet is 2.2 mm. Therefore, 4.6 mm is suitable as thediameter of the sleeve outlet 507, but the vortex tube may besufficiently operated with the diameter from 4.1 to 5.1 m. The vortextube of the present disclosure adopts the diameter of 4.5 mm at thesleeve outlet 507.

TABLE 1 [Comparative Example] Result of measurement of conventionalproduct shown in FIG. 1 (measure: ° C.) Classification 30% 32% 34% 36%38% 40% Average Cold Run 1 −34.2 −33.8 −32.9 −32.4 −31.2 −30.4 dischargeRun 2 −35.2 −34.4 −33.3 −32.9 −30.8 −30.9 temper- Run 3 −33.8 −33.5−33.7 −31.9 −30.5 −29.6 ature Run 4 −34.9 −32.9 −32.4 −32.8 −31.9 −31.1Run 5 −35.4 −34.8 −33.8 −31.4 −31.4 −30.2 Deviation 1.6 1.9 1.4 1.4 1.31.5 1.5 Average −34.7 −33.9 −33.2 −32.3 −31.2 −30.4 −32.6

TABLE 2 [Embodiment 1] Result of measurement of product of presentdisclosure shown in FIG. 2 (measure: ° C.) Classification 30% 32% 34%36% 38% 40% Average Cold Run 1 −36.5 −36.0 −35.8 −34.2 −32.7 −31.8discharge Run 2 −37.2 −34.5 −35.1 −33.7 −31.8 −31.2 temper- Run 3 −34.9−36.7 −34.1 −32.2 −33.3 −30.1 ature Run 4 −36.9 −35.3 −33.6 −34.9 −31.9−32.1 Run 5 −37.3 −35.9 −34.7 −32.9 −32.4 −31.5 Deviation 2.4 2.2 2.22.7 1.5 2.0 2.2 Average −36.6 −35.7 −34.7 −33.6 −32.4 −1.3 −34.1

TABLE 3 [Embodiment 2] Result of measurement of product of presentdisclosure shown in FIG. 3 (measure: ° C.) Classification 30% 32% 34%36% 38% 40% Average Cold Run 1 −38.5 −37.9 −37.5 −36.5 −35.2 −33.4discharge Run 2 −39.7 −38.8 −36.9 −35.1 −34.1 −32.1 temper- Run 3 −37.5−37.2 −38.2 −36.8 −35.5 −33.8 ature Run 4 −40.3 −38.4 −36.4 −35.4 −33.9−33.1 Run 5 −38.8 −38.1 −37.4 −36.2 −34.9 −32.5 Deviation 2.8 1.6 1.81.7 1.6 1.7 Average −39.0 −38.1 −37.2 −36.0 −34.7 −33.0 −36.3

FIG. 6 is a view showing a vortex tube with three generators by addingone generator to the vortex tube in FIG. 3.

The first generator and the second generator in FIG. 6 are designed withthe same structure as the first generator and the second generator ofthe vortex tube in FIG. 3. The third generator in FIG. 6 is manufacturedto have three wings and three air intake grooves of the same size likethe vortex tube in FIG. 3. Other numerical values are as shown in

FIG. 5. Therefore, the vortex tube in FIG. 6 has nine air intakegrooves, so the compressed air is supplied 41 to 43% more than thevortex tube in FIGS. 1 to 3.

TABLE 4 [Embodiment 3] Result of measurement of product of presentdisclosure shown in FIG. 6 (measure: ° C.) Classification 30% 32% 34%36% 38% 40% Average Cold Run 1 −35.5 −35.8 −35.1 −33.8 −32.2 −31.2discharge Run 2 −37.2 −33.9 −34.8 −32.9 −31.5 −30.5 temper- Run 3 −34.8−36.2 −34.1 −34.1 −32.9 −29.9 ature Run 4 −36.1 −35.6 −33.4 −34.5 −33.0−32.0 Run 5 −36.7 −35.4 −34.4 −32.6 −32.3 −31.3 Deviation 2.4 2.3 1.71.9 1.5 2.1 2.0 Average −36.1 −35.4 −34.4 −33.6 −32.4 −31.0 −33.8

FIG. 7 is a view showing an embodiment in which a counterflow preventioncap 150 is inserted in the hot air adjusting valve so that the vortextube may be operated even under external pressure. The counterflowprevention cap 150 is generally made of synthetic resin containingrubber properties, but may be made of metal with elasticity. Thecounterflow prevention cap 150 does not act as a resistor when heat isdischarged to the outside of the vortex tube, but when the outside airflows into the inside of the vortex tube, the counterflow prevention cap150 spreads to serve as the resistor.

Although a preferred embodiment of the present disclosure has beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the presentdisclosure as disclosed in the accompanying claims.

1. A vortex tube comprising: a cold and heat separation chamber; a coldair outlet provided at an end of the cold and heat separation chamber; agenerator provided between the cold air outlet and the cold and heatseparation chamber; a hot air outlet provided at another end of the coldand heat separation chamber and including a hot air adjusting valve; andan outer tube cover comprising a compressed air inlet and surroundingthe cold and heat separation chamber at a predetermined gap whileblocking the cold and heat separation chamber at an outside thereof, sothat introduced compressed air can be supplied into the generator,wherein the compressed air flowing through the compressed air inletgenerates rapid rotating wind by passing through the generator to bemoved into the cold and heat separation chamber to separate cold andheat from each other.
 2. The vortex tube of claim 1, wherein acounterflow prevention cap is inserted in the hot air outlet includingthe hot air adjusting valve.
 3. A vortex tube comprising: a cold andheat separation chamber; a cold air outlet provided at an end of thecold and heat separation chamber; a first generator, a sleeve, and asecond generator provided between the cold air outlet and the cold andheat separation chamber; a compressed air inlet provided at a portionclose to the first generator and the second generator and configured tosupply compressed air into the first generator and the second generator;and a hot air outlet provided at another end of the cold and heatseparation chamber and including a hot air adjusting valve, wherein anoutlet of the sleeve has a diameter larger than a diameter of anentrance of the cold air outlet and smaller than an inner diameter ofeach of the generators.
 4. The vortex tube of claim 3, wherein thesleeve is inclined such that an entrance of the sleeve has a diameterlarger than the diameter of the outlet of the sleeve.
 5. The vortex tubeof claim 3, wherein a diameter of an entrance of the sleeve coincideswith the inner diameter of the first generator.
 6. The vortex tube ofclaim 5, wherein the diameter of the outlet of the sleeve satisfies thefollowing equation.[diameter of entrance of cold air outlet+{(inner diameter of cold andheat separation chamber−diameter of entrance of cold airoutlet)/2±(inner diameter of cold and heat separation chamber−diameterof entrance of cold air outlet)/4}]
 7. The vortex tube of claim 3,further comprising: a third generator in addition to the secondgenerator.
 8. The vortex tube of claim 7, further comprising: a secondsleeve in which the third generator is provided, wherein a passage inthe second sleeve is inclined such that an entrance of the second sleevehas a diameter larger than a diameter of an outlet thereof.